He also distinguished himself as a Methodist pastor, as a college and seminary professor and theologian, and as an author and editor.
Heinrich, born in Nörten, Hanover, became an American citizen and was ordained into the Methodist Episcopal ministry.
John married Luella Elizabeth Stroeter (daughter of Ernst Ferdinand & Caroline Ströter) on 8 September 1896.
They had the following children: Albert E., Henry E., John Louis, Jr., and Marie L. Christianity • Protestantism Being a Methodist Pastor's family, the Nuelsens moved a great deal.
Nuelsen served pastoral appointments in Sedalia, Missouri and Sleepy Eye, Minnesota.
After three years this department was expanded into the Nast Theological Seminary, which served well in the training of ministers and workers in Christian vocations from 1902 until 1933, especially those of German descent.
This election was thus an early manifestation of the conviction, registered often in more recent years, that minority groups in the Church should furnish a part of the Episcopacy.
Once elected, however, Bishop Nuelsen was assigned, not to preside over German Conferences, but to a regular Area of the Church in the United States.
At first his Episcopal Area covered all annual conferences in Switzerland, Germany, Scandinavia, Russia, France, Spain, Italy and Austro-Hungary.
John Louis Nuelsen was honored with the degree of Doctor of Divinity in 1903 by the University of Denver.
His library, which can still be seen in the Methodist Publishing House in Zurich, bears silent testimony to the wide range of his interests and the eagerness of his mind for acquiring knowledge.
During the last period of the war he was in fact forbidden to travel, being immobilized in Switzerland for long months.